Malignant Triton tumour of labia majora- a case report

Abstract

Introduction- Malignant triton tumour
(MTT) is a relatively rare variant of malignant
peripheral nerve sheath tumour
(MPNST). It is defined as MPNST with
rhabdomyosarcomatous differentiation. It
is commonly located in head and neck, extremities
and trunk. We report a case of
Malignant triton tumour occurring in labia
majora.Case scenario - A 30 year old female
presented with nodules all over the
body. The nodules were initially seen in
the labia majora and left groin, at the time
of birth. She was diagnosed to have neurofibromatosis
type 1 in 2011. In view of
increased itching and bloody discharge
from the labia major, excision of left majora
was done in February of 2013, in a
general hospital. We received 7 slides and
8 blocks of that specimen for review. On
microscopic and immunohistochemical examination,
a diagnosis of malignant triton
tumour was made. She was treated with
radiotherapy in April 2013 and is disease
free till date.DiscussionPrimary malignant
peripheral nerve sheath tumour involving
vulva is extremely rare. Approximately 15
of
MPNSTs show heterologous elements
such as bone, cartilage and striated muscle.
Most of the reported heterologous
mesenchymal components are histologically
malignant. Along with the histological
features, immunohistochemistry aids in
the confirmation of MTT. The prognosis of
the MTT is worse than that of MPNST.
Leiomyosarcoma, Rhabdomyosarcoma,
MFH (pleomorphic undifferentiated sarcoma)
are most common differential diagnoses
for MTT. These are differentiated
on the basis of microscopic examination
and specific immunohistochemical markers.
Conclusion -Malignant triton tumour is
a very rare tumour and its occurrence in
labia majora is extremely rare, however
should be kept in differential diagnosis,
particularly in a setting of NF1, as it has
worst prognosis compared to MPNST.